> From: David Brownell <[EMAIL PROTECTED]>
> I should have said I was talking about shutting down after
> it gets the suspend request from PCI ... that is, when the
> driver is told to stop activity so the system can suspend.
> When OHCI is in the "UsbSuspend" state, it shouldn't
> be accessing memory. And that's the state it enters
> when it gets the suspend request ... from ACPI, via PCI.
> Right? Those PCI calls mean entering S3 or S4 states
> it seems ... it's not clear to me whether there are enough
> APIs to let device drivers (PCI or USB!) support C3,
> but I might well have missed some important ones.
C3 is a processor state, so device drivers needn't worry about it, except to
realize that constant bus mastering is causing the CPU to not enter as deep
a sleep as it potentially could. (IIRC a cpu in C2 takes more than half a
watt more than a cpu in C3.)
Alan mentioned doing less frequent polling when the bus is empty -- how hard
would it be to implement this? Would someone who knows the USB code be
willing to do it, or should I take a stab at it? I was thinking that if all
you are looking for is device insertion, you should only have to poll -
what? Once a second?
Thanks -- Regards -- Andy
----------------------------
Andrew Grover
Intel/TRL/MAL
[EMAIL PROTECTED]
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